In a reflector antenna[?], the relative reduction in the effective aperture of the antenna caused by the masking effect of other antenna parts, such as a feed horn or a secondary reflector, which parts obstruct the radiation path.
... (33%), Daimler-Benz (33%), Alenia[?] of Italy (21%), and CASA of Spain (13%).
Over the next five years, design work continued, aided by data from the British Aerospace ...